A quick introduction to computer memory usable
Everything on the computer is 0’s and 1’s.
A bit (short for binary digit) is the smallest unit of data in a computer. A bit can only store 0 or 1. Since a bit unit is too small to be much use on its own, data is stored in bytes, which are groups of eight bits.
Each purple line in the draw represents a bit.
Remember how we said that a bit is either a 0 or 1? So if we look at the amazing draw, each purple line can be equal to either 0 or 1. So, with that being said, there are 2 options for a bit to be equal to.
That means, that in every byte there are 2⁸ options, which is 256.
As we said, on the computer is all about 0’s and 1’s, so computers deal with powers of 2 naturally and 2 is the base of binary which computers use like 8 (2³), 1024 (2¹⁰), 1048576 (2²⁰), etc. Round numbers like 1000 (10³) is natural for us, but that’s because we have 10 fingers (or not, but either way, the fact that it is natural for us doesn’t mean that it is natural for the computer too). We often call 1024 (2¹⁰) bytes as “kilobyte” because it’s close to 1000, which is what kilo normally means.
Note: in 2000 The International Electrotechnical Commission or IEC proposed a notation scheme for the units based in powers of 2. The new names were created by replacing the second syllable in the old name by ‘bi’ (referring to ‘2’). A kilobyte must be now a kibibyte and so on. The new units also got corresponding symbols, so ’10 kibibyte’ is now written as 10 KiB instead of 10 kB
Anyway, let’s say that our system is a 32bit. We learned that 8 bits are 1 byte. So our system is a 4bytes.
According to the 4bytes draw, we can say that our system capacity is 2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2*2 or in shorter is 2³². We can also say that 2³² = 2³⁰*2².
Now, if we look at the file storage capacity by powers of 2 chart,
2³⁰ = 1Gigabyte. So 4bytes = 1Gigabyte * 2², which is equal to 4Gigabyte.
So, the maximum amount of memory usable in a 32bit computer is 4G.
The same thing will be for a computer with 64bit. Which is 2⁶⁴, that equals to 2⁶⁰*2²*2² => 16Exabyte.
